FIG. 1 schematically illustrates the architecture of a conventional spindle motor driving apparatus. As shown in FIG. 1, the conventional spindle motor driving apparatus connected to a spindle motor 130, and the spindle motor driving apparatus comprises a motor controller 110, a driving circuit 120, and a position sensor 140.
According to a rotating position of rotor of the spindle motor 130, the position sensor 140 generates a position signal H to the motor controller 110. According to the position signal H, the motor controller 110 generates a pulse width modulation signal PWM. According to the pulse width modulation signal PWM, the driving circuit 120 generates a first phase current Iu, a second phase current Iv and a third phase current Iw to three terminals U, V and W of the spindle motor 130. In response to the rotation of the spindle motor 130, the position sensor 140 issues the position signal H to the motor controller 110. For example, the position sensor 140 is a Hall sensor.
FIG. 2A is a schematic circuit diagram illustrating the driving circuit of the conventional spindle motor driving apparatus. As shown in FIG. 2A, the driving circuit 120 comprises six driving transistors M1˜M6. Each of the driving transistors M1˜M6 has a body diode connected between a drain terminal and a source terminal. Moreover, the pulse width modulation signal PWM comprises six modulation signals.
The gate terminal of the first driving transistor M1 receives the first modulation signal U_h. The drain terminal and the source terminal of the first driving transistor M1 are connected between a first power supply voltage V1 and a node u. The gate terminal of the second driving transistor M2 receives the second modulation signal W_I. The drain terminal and the source terminal of the second driving transistor M2 are connected between a second power supply voltage V2 and a node w. The gate terminal of the third driving transistor M3 receives the third modulation signal V_h. The drain terminal and the source terminal of the third driving transistor M3 are connected between the first power supply voltage V1 and a node v. The gate terminal of the fourth driving transistor M4 receives the fourth modulation signal U_I. The drain terminal and the source terminal of the fourth driving transistor M4 are connected between the second power supply voltage V2 and the node u. The gate terminal of the fifth driving transistor M5 receives the fifth modulation signal W_h. The drain terminal and the source terminal of the fifth driving transistor M5 are connected between the first power supply voltage V1 and the node w. The gate terminal of the sixth driving transistor M6 receives the sixth modulation signal V_I. The drain terminal and the source terminal of the sixth driving transistor M6 are connected between the second power supply voltage V2 and the node v. Moreover, the nodes u, v and w are connected to the three terminals U, V and W of the spindle motor 130, respectively.
FIG. 2B is a schematic timing waveform diagram illustrating the relationships between the pulse width modulation signal, the three phase signals and the position signal processed by the spindle motor driving apparatus of FIG. 1. The position signal H contains an A-component signal Ha, a B-component signal Hb and a C-component signal Hc.
In case that the phase of the rotor is in the range between 0 and 60 degrees, the first driving transistor M1 and the second driving transistor M2 are controlled by the first modulation signal U_h and the second modulation signal W_I, respectively. Under this circumstance, the first phase current Iu is positive, and the third phase current Iw is negative. That is, the driving current flows from the terminal U to the terminal W of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (100) is obtained.
In case that the phase of the rotor is in the range between 60 and 120 degrees, the third driving transistor M3 and the second driving transistor M2 are controlled by the third modulation signal V_h and the second modulation signal W_I, respectively. Under this circumstance, the second phase current Iv is positive, and the third phase current Iw is negative. That is, the driving current flows from the terminal V to the terminal W of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (110) is obtained.
In case that the phase of the rotor is in the range between 120 and 180 degrees, the third driving transistor M3 and the fourth driving transistor M4 are controlled by the third modulation signal V_h and the fourth modulation signal U_I, respectively. Under this circumstance, the second phase current Iv is positive, and the first phase current Iu is negative. That is, the driving current flows from the terminal V to the terminal U of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (010) is obtained.
In case that the phase of the rotor is in the range between 180 and 240 degrees, the fifth driving transistor M5 and the fourth driving transistor M4 are controlled by the fifth modulation signal W_h and the fourth modulation signal U_I, respectively. Under this circumstance, the third phase current Iw is positive, and the first phase current Iu is negative. That is, the driving current flows from the terminal W to the terminal U of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (011) is obtained.
In case that the phase of the rotor is in the range between 240 and 300 degrees, the fifth driving transistor M5 and the sixth driving transistor M6 are controlled by the fifth modulation signal W_h and the sixth modulation signal V_I, respectively. Under this circumstance, the third phase current Iw is positive, and the second phase current Iv is negative. That is, the driving current flows from the terminal W to the terminal V of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (001) is obtained.
In case that the phase of the rotor is in the range between 300 and 360 degrees, the first driving transistor M1 and the sixth driving transistor M6 are controlled by the first modulation signal U_h and the sixth modulation signal V_I, respectively. Under this circumstance, the first phase current Iu is positive, and the second phase current Iv is negative. That is, the driving current flows from the terminal U to the terminal V of the spindle motor 130. According to the A-component signal Ha, the B-component signal Hb and the C-component signal Hc, the position signal H indicative of (101) is obtained.
Then, the rotator is continuously rotated in the range between 0 and 360 degrees in cycles.
From the above discussions, each modulation signal of the pulse width modulation signal PWM has a 120-degree active period. For example, the active period of the first modulation signal U_h is in the range between 300 and 60 degrees, the active period of the second modulation signal W_I is in the range between 0 and 120 degrees, the active period of the third modulation signal V_h is in the range between 60 and 180 degrees, the active period of the fourth modulation signal U_I is in the range between 120 and 240 degrees, the active period of the fifth modulation signal W_h is in the range between 180 and 300 degrees, and the active period of the sixth modulation signal V_I is in the range between 240 and 360 degrees.
In other words, the motor controller 110 of the conventional spindle motor driving apparatus realizes the phase of the rotor of the spindle motor 130 according to the position signal H, and determines the 0-degree, 60-degree, 120-degree, 180-degree, 240-degree and 300-degree phase change points. Consequently, the active periods of the six modulation signals are correspondingly controlled. In case that the spindle motor driving apparatus has no position sensor to generate the position signal H, the motor controller 110 fails to accurately generate the six modulation signals U_h, U_I, V_h, V_I, W_h and W_I to control the spindle motor 130.